A supercharging pressure control device of an internal combustion engine which correctly learns a reference position of a wastegate valve to properly control a supercharging pressure is disclosed in Patent Literature 1 below. The supercharging pressure control device calculates a degree-of-opening correction amount of the wastegate valve on the basis of a deviation between a target supercharging pressure and a real supercharging pressure, calculates a fully closed learning value of the wastegate valve on the basis of the degree-of-opening correction amount on condition of post-completion of warmup of the engine, calculates a target degree of opening of the wastegate valve on the basis of the degree-of-opening correction amount, the fully closed learning value, and a base degree of opening of the wastegate valve, and has feedback control of a WGV actuator for driving the wastegate valve on the basis of the target degree of opening and a real degree of opening of the wastegate valve.
A supercharging pressure control device of a supercharger-equipped engine is disclosed in Patent Literature 2 below. The supercharging pressure control device controls a control gain of feedback to be large during a transition and to be small at a steady time.